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Position of Sun Calculator

Reviewed by Calculator Editorial Team

The Position of Sun Calculator determines the sun's position in the sky at any given time and location. This information is crucial for solar energy applications, astronomy, and understanding daylight patterns.

What is Solar Position?

The solar position refers to the sun's location in the sky, typically described by two angles: azimuth and altitude. These measurements help determine the sun's path throughout the day and its intensity at different times.

Key Solar Position Terms

  • Azimuth: The angle between the sun's position and true north, measured clockwise from north.
  • Altitude: The angle between the sun's position and the horizon.
  • Solar Time: The time corrected for the difference between solar noon and clock noon.

Solar position calculations are essential for solar panel installation, agricultural planning, and understanding seasonal variations in daylight.

How to Use This Calculator

  1. Enter your location's latitude and longitude.
  2. Select the date and time for the solar position calculation.
  3. Click "Calculate" to see the sun's azimuth and altitude.
  4. Review the results and chart visualization.

The calculator uses the SPA (Solar Position Algorithm) for accurate results. All calculations are performed client-side for your privacy.

Solar Position Formula

The solar position is calculated using the following formulas:

Julian Date (JD) = 367 * Year - floor((7 * (Year + floor((Month + 9) / 12))) / 4) + floor((275 * Month) / 9) + Day + 1721013.5 + (Hour - 12) / 24 + Minute / 1440 + Second / 86400

From the Julian Date, we calculate the following:

Solar Mean Anomaly (M) = 0.9856 * (JD - 2451545) - 3.289 Solar True Longitude (L) = M + 1.916 * sin(M) + 0.020 * sin(2 * M) + 282.9404 Solar Right Ascension (RA) = atan2(cos(ε) * sin(L), cos(L)) Solar Declination (δ) = asin(sin(ε) * sin(L))

Where ε is the Earth's axial tilt (23.439 degrees).

Example Calculation

For New York City (40.7128° N, 74.0060° W) on June 21 at 12:00 PM:

Parameter Value
Azimuth 180.0°
Altitude 73.6°
Solar Time 12:00:00

This means the sun is directly overhead at solar noon on the summer solstice.

Frequently Asked Questions

What is the difference between solar time and clock time?

Solar time is based on the sun's position, while clock time follows a standardized schedule. The difference varies throughout the year and by location.

How accurate is this solar position calculator?

This calculator uses the SPA algorithm, which is accurate to within 0.0003 degrees for most locations and times.

Can I use this for solar panel installation?

Yes, the solar position data helps determine optimal angles for solar panels to maximize energy production.